syscall allows you to call upon the basic system functions. To use syscall, first set $v0 with the code of the function you want to call, then use syscall. The exact codes available may depend on the specific system used, but the following are examples of common sytem calls.

code

call

arguments

results

1

print integer

$a0 = integer to print

2

print float

$f12 = float to print

3

print double

$f12 = float to print

4

print string

$a0 = address of beginning of string

5

read integer

integer stored in $v0

6

read float

float stored in $f0

7

read double

double stored in $f0

8

read string

$a0 = pointer to buffer, $a1 = length of buffer

string stored in buffer

9

sbrk (allocate memory buffer)

$a0 = size needed

$v0 = address of buffer

10

exit

Example: printing the number 12
li $a0, 12→;loads the number we want printed, 12 in this case, into the first argument register
li $v0, 1→;stores the code for the print integer call into $v0
syscall→;Executes system call